Analysis of Meiotic Telomere Functions

大多数生物体的有性生殖需要两个主要过程来改变染色体组的数量（倍性水平），减数分裂和受精。减数分裂将二倍体体细胞转化为单倍体配子细胞、精子细胞或卵细胞。受精时，来自精子和卵子细胞核的染色体结合恢复二倍体状态。因此，减数分裂不仅对通过繁殖维持基因组至关重要，而且也是染色体洗牌和重组发生的阶段，从而产生遗传多样性。尽管减数分裂在建立遗传规则中的作用在大多数高等生物中得到了很好的理解和保守，但对减数分裂过程中控制遗传物质洗牌和分类的分子过程知之甚少。线状染色体的特化末端，端粒，在减数分裂时聚集在核膜上，形成现在称为花束的排列。本文以玉米（Zea mays, corn）为模型系统，研究端粒在减数分裂中的作用。基因突变体正在筛选端粒染色显微镜，以允许检查在减数分裂期间端粒聚集和染色体分离之间的关系。该项目将导致玉米端粒结合蛋白的鉴定和表征。这些端粒蛋白可能介导减数分裂染色体行为的某些方面。编码玉米端粒蛋白的基因将被分子克隆并分析其在减数分裂中的可能功能。由这些克隆DNA片段编码的蛋白质将被测试其与双链端粒DNA特异性结合的能力。这项工作将促进对减数分裂基本机制和端粒生物学功能的认识。

Sexual reproduction in most organisms requires two major processes that change the number of chromosome sets (ploidy level), meiosis and fertilization. Meiosis converts diploid somatic cells into haploid gamete cells, the sperm or egg cells. At fertilization, the union of chromosomes from the sperm and egg nuclei restores the diploid state. Not only is meiosis therefore essential for genome maintenance through reproduction, but it is also the stage at which chromosome shuffling and recombination occurs, producing genetic diversity. Although the role of meiosis in establishing the rules of inheritance is well understood and conserved across most higher organisms, relatively little is known about the molecular processes that govern the shuffling and assortment of genetic material during meiosis. The specialized ends of linear chromosomes, the telomeres, cluster together on the nuclear envelope at meiosis in an arrangement now referred to as the bouquet. The work summarized here uses maize (Zea mays, corn) as a model system to investigate the role of telomeres in meiosis. Genetic mutants are being screened by telomere-staining microscopy to permit examination of the relationship between telomere clustering and chromosome segregation during meiosis. This project will result in the identification and characterization of telomere-binding proteins from maize. These telomeric proteins are likely to mediate some aspects of meiotic chromosome behavior. The genes encoding maize telomeric proteins will be molecularly cloned and analyzed for information related to their possible function at meiosis. The proteins encoded by these cloned DNA segments will be tested for their ability to bind specifically to double-stranded telomeric DNA. This work will advance knowledge of the basic mechanisms of meiosis and the biological function of telomeres.